Using the bathroom? Really? That’s what this is going to come down to?

Because that’s the obsession of just about anyone who is still vexed by the idea that transgender Americans should be protected from discrimination: the restroom thing.

It’s the first thing folks ask me when they want to know how Tyler — who was born a girl but enrolled in kindergarten at my son’s school as a boy three years ago — is doing.

“But where does he go to the bathroom?”

Answer: He uses the boys’ bathroom, just like all the other boys at school. And not once in three years of boy toilet use has anything happened surrounding Tyler, now 8, that is more unseemly than the usual stuff boys do in school bathrooms.

Yet that was the main point from hundreds of parents who whooped, whistled, hollered and thunderously applauded at a Fairfax County School Board meeting last week when speakers raged against a change in school anti-discrimination policy to include “gender identity.”

One mother, Jun Yuan, said that her 7-year-old daughter is so shy, she locks the bathroom door and doesn’t even want her mom to see her pee.

Amen. I don’t want anyone to see me pee, either. (Although everyone who got a card or flowers on Sunday for Mother’s Day knows that’s not really possible as a mother.)

Yuan is terrified of what will happen when a child who looks different under her dress locks herself in a stall and privately relieves herself.

The horror!

“It will increase sex crimes to little children as young as 5 years old,” Yuan told the School Board as the audience roared with approval. “Stop this proposal. Do not hurt our children,” she said, generating more whistles than a call for a Prince encore.

For shame, parents. I hope that any child wrestling with gender identity never, ever sees that School Board video of adults behaving so badly.

The bathroom can be a terrifying place for most transgender people, and it’s heartbreaking to see parents use fear-mongering and a right to privacy as the way to further hurt one of America’s frequently abused populations.

What about locker rooms? Usually, there are stalls. And they’re almost always full and fought over by kids who also want privacy from changing in front of their cruel, same-sex peers. You don’t think that exists? Think back a minute to the training-bra and peach-fuzz days.

Add a few more partitions, the gender-conforming kids will be delighted, trust me.

The other thing parents seemed to be frightened of is an alleged lack of control over “sex and sexuality” education for their children.

Casey Mattox, a lawyer with the Alliance Defending Freedom, testified at the School Board meeting Thursday that he was pleased that he could opt his 9-year-old daughter out of the sex education class her peers took. (Good luck with that, because kids totally don’t talk to one another. And I’m certain that no one is passing Judy Blume books around.)

Mattox said that with the inclusion of “gender identity” in the school policy, his control over his daughter’s education on sex would be eliminated.

Um, Mr. Mattox? Gender identity is not about sexuality. It is about whether a person feels they are male or female, despite the below-the-belt organs they were born with.

The official name is gender dysphoria, and after 14 years of study and revision, it appears in the newest edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders. That’s the bible of mental medicine that includes definitions of better-known things, such as PTSD, gambling addiction, anorexia nervosa, insomnia and bipolar disorder.

And you know what’s funny? Of all the complex and difficult ways to tackle some of the other conditions in the psychiatric association’s manual, this one is usually pretty simple. The cure? Usually all it takes is allowing that person to live with the gender they identify with.

America is watching a painful and public transition as Olympian Bruce Jenner rebirths as the person who’s been struggling for decades to emerge. Imagine the pain a child with the same condition is in and how parents could help ease it.

This edition of the manual deliberately removed gender dysphoria from the category of sexual disorders and removed any reference to sexual orientation, because that’s not what gender identity is.

Associating this condition with rape or sexual education is the same as saying that pink sundresses or Spider-Man shirts are about sex, too. They are not. And please, parents who haven’t taken the time to understand this real medical condition, stop it with all the sex thoughts! That’s about you, not the kids.

The Fairfax School Board passed this change with one abstention and one “no” vote. But parents and some local clergy are still fighting it.

The way I learned about a transgender child in our school?

My son explained it to me. One day, he matter-of-factly said: “It just means that [Tyler] has a boy brain but was born into a girl body.” And they’ve all resumed playing Star Wars and Lego and pirates ever since.

Give your kids a little more credit, Fairfax parents. They are more tolerant, more understanding, more accepting and far more worldly than we were growing up.